Liquid water on Mars?

Images of the lander's legs suggest the spacecraft may have kicked up droplets of liquid water when it landed on Mars in 2008 (colour added for emphasis).

A chemical called perchlorate, which was discovered at the site, could act as an anti-freeze, keeping the water liquid. But it might also make the droplets too salty to support life. Less salty pockets of water could lurk beneath deposits of ice and snow, warmed by a form of the greenhouse effect. (Image: NASA/JPL-Caltech/University of Arizona/Max Planck Institute.)

Water on the moon

The hunt for water on the moon has lasted for decades. This year, three separate spacecraft found evidence that water may in fact be widespread, clinging to the lunar soil. Hydrogen in the solar wind is thought to create the water when it collides with oxygen-rich materials on the lunar surface. Although the water exists in trace amounts, some researchers suspect it could be harvested by heating the soil with microwaves.

The moon's biggest cache of water may lie at the poles. Bucketfuls of the stuff were kicked up in October, when NASA's LCROSS satellite sent a spent rocket stage crashing into a permanently shadowed crater on the moon's south pole. (Illustration: University of Maryland/F. Merlin/McREL)

NASA needs at least $3 billion more per year to send astronauts beyond low-Earth orbit, the committee found. They also called into question the utility of NASA's Ares I vehicle. The rocket is designed to loft astronauts into orbit after the space shuttle retires in 2010, but it may not be ready until 2017, two years after the International Space Station is set to be scuttled. NASA is still awaiting a decision by Obama on its future direction. (Illustration: NASA)

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Satellite crash

The problem of space junk took on heightened urgency this year, in the first ever collision of two intact satellites. More than 1500 new pieces of space junk larger than 10 centimetres were created in the February smashup between a defunct Russian Cosmos 2251 satellite and US Iridium 33 communications satellite.

Space flotsam is a growing issue. Some 19,000 orbiting objects at least 10 cm across are currently tracked by the US Air Force. The United Nations and a number of national space agencies have now agreed on measures to mitigate the growth of debris, but future collisions and launches are expected to cause the amount of debris to balloon. (Illustration: Analytical Graphics, Inc. (www.agi.com))

New space telescopes

In a €2 billion gamble, the European Space Agency successfully launched two pioneering telescopes aboard the same rocket in May. Boasting a mirror (pictured) almost four times as big as NASA's Spitzer, the infrared-sensitive Herschel Space Observatory is the largest telescope to be sent into orbit. It will study cool celestial objects, from comets and asteroids in our own solar system to some of the universe's most distant galaxies.

Herschel's launch companion, Planck, will map the cosmic microwave background (CMB), relic radiation from the big bang, with roughly 10 times the sensitivity of NASA's WMAP satellite. Planck could yield the first evidence of gravitational waves that are thought to have rippled through space-time as a result of inflation – a period just after the big bang when the universe rapidly expanded in size. (Image: ESA)

Spirit struggles for life

2009 has not been a banner year for NASA's Mars rover Spirit. After five years roaming the Red Planet, the plucky explorer came to a halt in April when its wheels became mired in soft sand. Worried that attempting to move the rover could make the situation worse, NASA used two prototype rovers to test escape manoeuvres in a sandbox in California. Spirit made its first attempt to leave the area in November, some seven months after it got stuck.

Mission managers concede the rover may not escape. Winter is approaching, and it could cause the rover's solar-power levels to drop dangerously low before it can escape. Spirit has also encountered a new technical glitch. The rover has been dragging one of its wheels since 2006. A second wheel stalled in November. If it cannot be revived, the rover may be permanently stranded. (Illustration: NASA/JPL)

Most distant object

A flash of gamma-ray light spotted by NASA's Swift satellite in April was found to come from the most distant object in the universe yet spotted. The burst came from a self-destructing star that exploded just 630 million years after the big bang. The distance makes the now-dead star the earliest object to be discovered from an era called reionisation, which occurred within the first billion years after the big bang. At that time, an obscuring fog of neutral hydrogen atoms was being burned off by radiation from the first stars and galaxies. Finding more such bursts could shed light on this process. (Image: Gemini Observatory/NSF/AURA/D. Fox/A. Cucchiara/E. Berger)

Alien worlds

More super-Earths, planets up to 10 times as massive as Earth, were found this year than in any previous year. But Earth-sized planets, potentially the best environments for life, remained elusive. The lightest to be found orbiting a normal star is a world called MOA-2007-BLG-192-L b. Originally thought to be 3 Earth masses, it is now believed to weigh just 1.4 Earths.

NASA prizes

The competition in NASA's Centennial Challenges programme, intended to spur the development of new technologies, heated up this year. Controversy erupted in October after organisers at a mock lunar lander competition allowed a team extra time to try for the $1 million first prize, resulting in an upset that saw the favoured team walk away with second prize.

Also in October, a robot picked up and deposited more than 440 kilograms of mock moon dust, becoming the first winner in NASA's Regolith Excavation Challenge, which was held for the third time this year. In November, two designers took home $350,000 for glove prototypes that are easier to bend and use than NASA's current model. (Image: Tony Landis/NASA Dryden)

Zapped from afar

Space radiation hit a record high this year. According to measurements from NASA's Advanced Composition Explorer spacecraft, galactic cosmic rays – speeding, charged particles from outside the solar system – are 19 per cent more abundant now than at any time in the last 50 years. The culprit is the sun's magnetic field, which helps shield the solar system from cosmic rays. The sun is at a minimum in its 11-year cycle of magnetic activity, and this particular dip is deeper than any other seen in nearly a century. (Image: SOHO Consortium/EIT/ESA/NASA)

Dark matter hints

In December, the Cryogenic Dark Matter Search collaboration, which operates detectors in an abandoned iron mine in Minnesota, reported a tantalising glimpse of what could be dark matter, the mysterious stuff that is thought to outweigh normal matter by about six to one. The detectors counted two possible hits in data collected in 2007 and 2008, when only 0.8 events were expected. The results are not statistically significant, but there is more data to come. The experiment is also expected to boost its sensitivity in 2010.